In a Global System of Mobile communication (GSM), generally, one Base Station Controller (BSC) can only connect one Mobile Switch Center (MSC) which can also be called Mobile Switch Center emulator (MSC), as shown in FIG. 1.
BSC multi-homing networking means that one BSC can connect more MSCs, as shown in FIG. 2. A Serving Node Selection Function (SNSF) is responsible for selecting the MSCs, distributing services to each MSC through a certain algorithm for processing and realizing load sharing among the MSCs by dynamically adjusting the distribution, such as A-Flex in the field of Code Division Multiple Access (CDMA) and lu-Flex in the field of Wideband-CDMA (WCDMA). Generally, the SNSF is set inside the BSC.
Under the BSC multi-homing networking mode, if an MSC fails due to a certain reason, the SNSF will not distribute new services to the MSC, and share and distribute new services of a terminal, which are originally distributed to the MSC, to other MSCs. At the same time, all the existing services on the MSC will be interrupted once the MSC fails.
When a certain MSC is to be subjected to operations such as upgrading or removal or is not needed due to some reasons, this MSC failure will be caused artificially. In this way, new services of a terminal that are originally distributed to the MSC will be redistributed to other MSCs. But all the existing services on the MSC will be interrupted once the MSC fails, then it will cause serious call loss and bring other problems. For example, a terminal originally distributed to the MSC cannot be called until it is autonomously registered with other MSCs.
In the WCDMA, Radio Network Controller (RNC) multi-homing networking means that one RNC connects more Serving General Package Radio Service Support Nodes (SGSNs); under such networking mode, the above-mentioned problems also exist when a certain SGSN is subjected to upgrading and other operations. The RNC multi-homing networking mode is shown in FIG. 3.